With the rapid development of communications technologies, wideband code division multiple access (Wideband Code Division Multiple Access, WCDMA), as one of the main technologies in the 3rd generation mobile communication system, is widely researched and applied worldwide. In a current WCDMA system, a single antenna is used for uplink transmission. In order to further improve an uplink transmission rate of the WCDMA system, and shorten a data transmission delay, a multi-antenna technology is required in the uplink to bear data.
FIG. 1 is a schematic diagram of a principle of downlink MIMO (Multiple Input Multiple Output, multiple input multiple output) in the prior art. As shown in FIG. 1, W1, W2, W3, and W4 are called weighting factors of data blocks (Blocks), where
      W    ⁢                  ⁢    1    =      1          2      and W2 is precoding information that is fed back by a user equipment (User Equipment, UE) to a Node B (Node B). The value of W2 may be selected from the following set, for example,
      w    2    ∈      {                                                      1              +              j                        2                                                              1              -              j                        2                                                                              -                1                            +              j                        2                                                                                                                    -                    1                                    -                  j                                2                            }                        .                              
(W1, W2) is called a primary precoding vector that is used to perform weighting on primary data blocks, while W3=W1, and W4=−W2. (W3, W4) is called a secondary precoding vector that is used to perform weighting on secondary data blocks.
A MIMO dual stream refers to two different data blocks scheduled by the Node B each time, where one is a primary data block and the other is a secondary data block. A MIMO single stream refers to a single data block scheduled by the Node B each time. A data stream corresponding to a primary data block is a primary data stream, and a data stream corresponding to a secondary data block is a secondary data stream. In the prior art, the Node B may schedule a downlink MIMO dual stream, or may schedule a downlink MIMO single stream. Switching between the downlink MIMO single stream and the downlink MIMO dual stream is controlled by the Node B. For example, the Node B decides whether to schedule the downlink MIMO dual stream or the downlink MIMO single stream at a next time according to the channel quality and precoding control indication fed back by the UE and in combination with the actual condition of the Node B. In the prior art, since the uplink MIMO technology is still under research, no relevant solutions are available currently to switching from a dual stream to a single stream in an uplink MIMO mode.